bringing literally everything you did to apply for the visa you got approved for, is ridiculous. You can defend their routines if you want, it doesn't change the fact that it's a silly requirement, when you literally just fly in and out and get the same extension without the paperwork.
You need to book flight to apply for a visa to any country.
But just book a fully refundable one if you want to be sure. You don't even have to use that ticket or fly on that date once your visa is approved anyway.